GRAHAM HAVILAND

Symposium Presentation Title: Functionality of the Short Wave Sensitive Opsin in Euarchonta

Symposium Presentation Abstract: The short wave sensitive opsin gene (SWS1) codes for a photosensitive pigment found in the s-cone cells of the retina in the mammalian eye. While it was once hypothesized that nocturnal mammals lost opsin functionality due to the limited utility of color vision in low light environments, studies have shown that many have in fact retained functional opsin genes. We used PCR techniques to sequence the SWS1 gene in species of the three closely related orders that comprise the grandorder Euarchonta: Scandentia, Dermoptera, and Primates. These sequences were examined to determine the functionality of the gene in each taxon and, where possible, the wavelength to which the gene is tuned. Lastly, we generated a gene tree for SWS1 using six species of mouse lemur (Microcebus).

Original Project Description: Scientists generally accept that the ancestral mammal was nocturnal, and predicted that nocturnal mammals would have a retina containing only rod cells. Rod cells contain rhodopsin, a photo pigment that responds to low light levels. Surprisingly, studies determined that cone cells are present in the eyes of many nocturnal mammals. Scientists were further surprised to discover that many nocturnal mammals have two sets of photo pigment genes in addition to the rhodopsin found in rods. In other words many nocturnal mammals have the genetic capacity for dichromatic (or color) vision. Are the photo pigments "tuned" to the animal's unique light environment?” Using DNA from both diurnal and nocturnal mammals collected from Malaysia, we will examine and compare the photo pigment genes between taxa.

Research methods and techniques: REU Interns will receive training and participate in, DNA extraction, PCR, and sequencing in the Museum's core genetics facility, the Pritzker Laboratory and the DNA Discovery Center. In addition, they will participate in data collection, assembly and analysis.